PN junction - advanced modeling

1) A silicon diode has been characterized and as result we have a built-in potential of 0.53 V and a zero-bias capacitance of 1.3 mF/m^2. Assuming an abrupt junction (the measured grading coefficient is 0.5!) what are the respective doping levels on the p and n side? I don't find any real value that satisfies this condition...so how is it possible in a real device to have this values?

Now the non-standard:

2) In a p-n junction with linearly graded profiles anyone knows about the space charge region at equilibrium. What happen during a biasing? What about the electric fields inside the semiconductor?

3) How to use the result of a PN junction for the real 3D structure? I mean...what is considered as "Area" and what as "p-side length" or "n-side length" assuming a parallelepiped diffusion?